Why not set up a simple toggle switch on their patch panel or if convenient, have them plug in the cord when they use the room? A locking jack would require them to always mess with a key.

in a similar situation I gave each tenant a labeled jack in the conference room , then on each data panel used a red patch cord (the others where blue ) with a tag on it reading "conference " and had them plug it in when they wanted to use it then unplug when they where done